1. Field of the Invention
The invention relates to a mold for injection molding and to a method of operating a mold for injection molding.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. H05-245888 and Japanese Unexamined Patent Publication No. H11-151735 disclose a typical resin injection molding process. The known process starts with a movable mold closed relative to a fixed mold to define a cavity therebetween. The process continues by filling a molten resin into the cavity between the fixed and movable molds, and cooling the resin to solidify it. The movable mold then is separated from the fixed mold. An ejector pin then is driven from its initial position to a thrust-out position, thereby taking a molded article out of the mold. The ejector pin then is returned to the initial position, and the movable mold is moved towards the fixed mold to close the mold again.
The above-described step of removing the molded article from the mold must follow the mold-opening step. Thus, time is required to open the mold and additional time is required to take the molded article out of the mold. Further, the molding apparatus requires an ejecting device with a hydraulic cylinder for moving the ejector pin. The ejecting device requires considerable space.
The present invention was developed in view of the above problems and an object thereof is to shorten a molding cycle and to make a mold and a molding apparatus smaller.